Piston



2 Sheets-Sheet 1 PISTON S. D. HERON Filed NOV. 7, 1931 I f lggf lm ll April 3, 1934.

April 3, 1934.

s. D.' HERON 1,953,109

PISTON Filed NOV. 7, 1931 2 Sheets-Sheet 2 5O 5/ IO ///////4mV/// a Patented Apr. 3, 1934 UNITED STAT ES PATENT? OFFICE 1,953,109 7 I ms'roN Sani D. Heron, Dayton, Ohio Application November 7, 1931, Serial No. 573,557

' 11 Claims. (01-123-416) This invention relates to pistons of the'type usedin combustion engines and the like.

One object of the invention is the provision I of an engine piston .having an insert member providing a sealed chamber containing a qua'n' tity of cooling medium providing for the effective transfer of heat from the piston head to the skirtportions, the insert member forming. a rigidifying brace or connection from the inner ends of the piston pin bosses to the piston head.

the novel method of forming a piston, in which the piston pin bosses are passed'through the walls of the piston skirt and an insert member, these parts then being hydrogen brazed together.

Additional objects and advantages of the invention will be apparent from the following description, the appended claims and the accompanying drawings, in which a few modifications of the invention have been illustrated, and in which,-- a

Fig. 1 is a central vertical section through a piston constructed in accordance with the present invention;

Fig. 2 is a section on the line 2-2 of Fig. 1; Fig. 3 is a bottom plan view of a portion of the piston;

Figs. 4 and 5 are sections corresponding to Figs. 1 and 2 respectively, but showing the piston in the course of construction;

Fig. 6 is a central vertical section of a of a piston, showing a modified form of construction; and

Fig. 7 shows a further modified form of construction.

Referring'more particularly to the drawings by reference numerals, 10 and 11 respectively designate the piston head and piston skirt portions of a hollow piston-adapted for use in an internal combustion engine, or in a compressor or the like where the dissipation of heat is a problem. As shown in Figs. 1 to 3 inclusive the head and skirt portions 10 and 11 are formed portion integrally preferably in the formyoi a steel forging.

In order to heat from the hot piston head down to the cooler provide for effective transfer of piston skirt portions the pistonis hollow and Q0- is provided with a suitable quantity of f-medium which is maintained in a state'ot bulence and agitation by the reciprocating movetsof the piston. The cooling medium employed is a liquid at'the normal operating tem- .peratures of the piston. Metallic sodium, potassium or lithium, or-mixtures of these metals or their nitrates or, equivalent salts, may be employed as the cooling'medium, as indicated'at 12. chamber 13 of which the cylinder head 10 and skirt llform outer walls, while an inner wall is provided by an insert member designated generally 15. This ins'ertmember is provided with The cooling medium 12 issealed in the i a generally cylindrical wall 16 through which the inner ends of the piston pin bosses 14 extend. The outer ends ofthe piston pin bosses 14 are securely fixed in openings provided in the skirt 1 1. Extending upwardly from the cylindrical wall 16 of the piston insert is a wall or walls that brace theinner ends of the piston pin bosses directly to the lower side .of the piston head. Thus, as shown Fig. 1, there is a generally conical wall 1''! that extends up and abuts against thecentralportion oi? the piston head at the lower side thereof and thus directly interbraces the piston head with the piston pin bosses. An additional wall 18, shown in cylindrical form, may also be employed to brace the inner ends of the piston pin bosses up to parts of the. piston head spaced from its center. The walls 18 are provided with fairly large sized openings 19 permitting the free flow of cooling medium from one end of the piston to the other during operation. The upper ends of the walls 18 are preferably arranged so as to fit'within a depression or socket 20 provided in the lower side of the piston head, the latter having a downwardly projecting ridge 21 that forms a seat for the irmer side of the top of the wall 18.

Extending upwardly from the lower end of the cylindrical wall 16, is an additional bracing wall 23 which, like the wall 18, extends ,through the cooling medium chamber 13and interbraces the insert member with the head portion of the piston. As shown, the wall 23, which is provided with holes 24, abuts against the inside of the piston head portion at 26, and is of frusto -conical shape, extending downwardly from the point of connection at 26 to the lower end of the insert wall 16.

It is also provided with holes for the passage of the piston pin bosses 14, and may be either an integral part with the insert wall 16, or a piece that is welded on to the wall 16.

At the bottom of the insert the latter is provided with an outward flange 28 provided opposite a flange 29 on the lower side of the piston skirt. Cooperating with these flanges, and forming a closure between the piston skirt and the wall 16, is a flat annular metal plate or ring 30, this ring, as shown in Fig. 2, providing a filling passage which is sealed by the plug 32. This plug is threaded into a disk 33 which is integrally connected at 34 to the ring 30. The plug 32 and the passage it closes through the ring 30 forms a convenient means for the supply of cooling medium to the piston, and provides for the effective seal of the cooling chamber.

Suitable piston ring grooves 36 are machined in the outer wall of the piston, and in order to provide for the relief of oil collected on the sides of the piston during operation the latter is provided with an oil collecting groove 37 provided below the piston ring location. Oil collected in this groove is relieved by flowing through an oil duct 38. This duct is formed by a pipe that is integrally united at'its outer end to the outer piston wall, and at its inner end to the wall 16 of the insert member, the pipe passing through both of these portions so that the oil may travel directly through the cooling chamber without interfering with the proper seal of the chamber. As shown, the oil duct 38 may be inclined downwardly and inwardly from the oil groove 37.

In the construction of the piston, the head and skirt portions 10 and 11 are formed separately from the insert member 15. The insert member is formed by suitably connecting together separate pieces to provide the several walls 17, 18 and 23, or these parts may be formed in any other desired manner. The insert member is then applied within the head and skirt portions of the piston, and the piston pin bosses 14 are then forced through the holes in the walls of the skirt and the insert member, leaving projecting portions 40 and 41 at their ends, as shown in Fig. 4. The oil ducts or pipes 38 are then applied by forcing them through the piston wall 11 and the insert wall 16, leaving projecting ends 43 and 44. The plate 30 is then applied against the flanges 28 and 29. Before this plate 30 is moved into place it is provided with a hole 45 and the reduced end of a disk 33 is pushed through the hole and the reduced end flared out or formed as shown at 46 so as to hold the disk 33 on the plate 30 during the uniting step of the process. The various parts of the assemblage are then ready to be united together. This step is preferably accomplished by hydrogen brazing the parts together at the same time, although any other equivalent process may be employed. Before the hydrogen brazing step, the projecting ends of the piston pin bosses 14 and the oil pipe 38 are encircled by copper wires 48, and copper rings or wires 49 are applied around the edge of the flat disk 30. Powdered material or wire is also applied to the joints at 50, 51 and 52, and also at 53 and 54, and the insert member is preferably spot welded or riveted to the piston head to hold the parts in place during the brazing step. The entire assemblage, with the head side extending downwardly, is then heated to the proper temperature in an atmosphere of hydrogen so as to form a firm and pressure-tight bond between the several parts and provide a tightly closed chamber for containing the cooling medium.

After the several parts of the assemblage have been united into a rigid assemblage, the outside walls of the piston are machined, which removes the projecting ends 41 of the piston pin bushings and the projecting ends 43 of the oil duct pipes. After the hydrogen brazing step the proper heat treatment may be given to the piston, for example by cooling the assembly from about 2100 F., the hydrogen brazing heat, to approximately 1700 and then cooling in air, oil or water, followed by a drawing heat. Preferably the assembly will be allowed to cool to room temperature and reheated for heat treatment. The outer walls may then be nitrided, chromium plated, or coated with other suitable bearing material.

After the machining operation is completed and the heat treatments given, the cooling chamber is partly filled with metallic sodium or other cooling metals or salts to the proper level, the cooling medium being supplied through the passage in the disk 30. After the proper amount of material is added to the piston, the plug 32 is screwed into the tapped hole that has been machined in the disk 33 during the machining operation so as to permanently and tightly seal the cooling medium against all leakage.

Cooling material of the character herein referred to is a solid at normal room temperature, although it is a liquid at a temperature of several hundred degrees F. It will be apparent that during engine starting conditions, or in fact even during certain running conditions the cooling medium might remain a solid in the skirt portions of the piston in the absence of a metallic connection or heat path from the cooling medium to the piston head, independent of the heat path provided by the outer walls of the piston itself. These outer walls are in contact with the cylinder walls, and'therefore cooled to a certain extent but the mechanical connection extending from a central portion of the lower side of the piston head to the part of the piston containing the cooling m dium insures that the cooling medium will be a liquid and thus effective in the transfer of heat a short time after the engine starts operating.

Fig. 6 shows a modified form of construction in which the cooling medium is supplied through an opening 50 in the piston head. This opening 50' is preferably a tapered hole that can be sealed tightly by a plug 51 which may be welded over at the top after the cooling medium has been added. In this form of construction the cooling medium is contained in a chamber 52 formed by the pressed metal skirt portion 53, the head forging 54', and the insert 55 which is of generally conical shape, having a frusto-conical wall 56 joined to the bottom of the piston skirt, and having a conical top portion 57 that abuts against the center of the lower side of the piston head so as to brace the piston head directly to the inner ends of the piston pin bosses 59. The piston pin bosses project through flanged openings in the piston skirt and insert walls, as shown, to which they are brazed or otherwise firmly and tightly secured. An oil collecting groove 60 is provided behind one of the piston ring grooves 61, and one or more oil relief ducts 63 project from the piston head over through the wall 57 of the piston insert. It is to be understood that the several parts of the assemblage are all united together, preferably by hydrogen brazing in the same manner as that described with reference to the construcconstructing it in two symmetrical halves and welding. the-two halves together, after which the halves may be insertd'intothe piston head-and skirt, the skirt 53 at the sametimebeingapplied' to the piston head. The piston pin bushings are then, moved longitudinally or' axially into their proper positions and the entire assemblage 'th 'n' construction.

hydrogen brazed to'provide a rigid and strong In accordance with Fig. 7, the insert is of slight- 1y modified form. The .insert designated generally 65 comprises'an annular shell 66 abutting at 67 against the lower side of the piston head 68; The piston pin bosses 69 are hydrogen brazed or otherwise secured to both the insert 65 and the pressed steel skirt portion '70 of the piston. The upper portions of the insert are provided with holes 72 for passage of the cooling medium that may be supplied through the tapered plugged passage 73. This cooling medium is permitted free access to all points on the under side of the piston head, the upper wall of the insert being formed by the plate 75 that is hydrogen brazed at 76 to the sidewalls of the insert member. It willbe noted thatin this construction as in the forms oi the invention previously described, the'inner ends of the piston pin bosses are directly braced up to the lower side of the piston head,

While the method herein described, and the forms of construction produced thereby, constitute preferred embodiments of the invention, it is to be'understood that the invention is not limited to this precise method andfforms of construction, and that changes may be made in either .without departing fromthe scope of the invention which is defined in the appended'claims. What is claimed-is: 1. A piston comprising head andskirtportions and a member provided therein and forming ,a. tightly closed chamber therewith, piston 'pin bosses mounted at. one end in said skirt portion and at the other end in said member, said mem- -ber extending to the inner sideof the head portion so as to brace an, inner part of the head portion directly to the inner ends of the piston pin bosses, and aquantity of coolingmedium. which is a liquid at the normalworking tempera-,

ture partly filling and sealed in said chamber.

, '2. A piston comprising head and skirtportions and a member forming a tightly closed chamber with the head and skirt portions, piston pinbossesmounted at one end in said skirt portion and at the 'bther': end in said member, said member having a plurality of-wallsextending from the inner'ends'of said 'pis'tori'pimbosses to the inner sideof saidhead portion sodsgto, brace difierent parts of the head portion directly to the inner ends of the piston pin bosses, and a quantityof cooling medium sealed in said chamber.

3. A piston comprising head and skirt portions and a member "hydrogen brazed therein and forming a tightly closed chamber with the head and skirt portions, piston pin bosses hydrogen brazed at one end in said skirt portion and at the other end in said member, said member having a plurality of walls extending from the ends of said piston pin bosses to the inner side of said head portion so as to brace difierent parts of the fanda member iormingatightly closed chamber piston pin bosses'a nd abutting against the cenwith the head andskirt portions, piston pin bosses mounted at one end in said skirt portion and at the other end in said member, said member hava'conical wallfextending'upwardly from said 80 ter of said head portion, and a quantity of cooling medium which is a liquid at the normal working temperature partly filling and sealed in center of said head portion, an annular wall extending through said chamber and bracing said member, to outer portions of the piston head, and a quantity of cooling medium which is a liquid at the normal working temperature partly filling and sealed in said chamber.

6. A piston comprising head and skirt portions, piston pin bosses secured at their outer ends in said skirt portion, a flat' hollow ring secured within the lower end of said skirt portion, and a member secured to the inner side of said ring and to the inner ends of the piston pin bosses, said ring, member, skirt portion. and head portion forming a tightly closed chamber, and a quantity of cooling medium which is liquid at the normal working temperature partly filling and sealed in said'chamber.

i 7. A piston comprising head and skirt portions, piston pin bosses'secured at their outer ends in said skirt portion, a flat. hollow ring secured within the lower end ofjsaidskirt portion, a passage through said ring throughwhich cooling medium maybe supplied, means; tightly sealing said passage, and a member secured to the inner side of 115 saidring and to the inner ends'of the piston pin bosses, said ring, member,- skirt, porton and head portion forming a tightly closed chamber, and a quantity of cooling medium whieh is liquid at the normal working temperature partly filling and sealed in said chamber; 3

, '81. A piston comprising head and skirt portions and a member forming a tightly closed-chamber. with the head and skirt-portions, piston pin bosses mounted at one end in said skirt portion and at the other end in saidmember, a quantity of cool- ,Iing-medium which is a liquid at the normal workingitemperatureof the piston partly filling and sealed in said; chamber, av passage in said head portion for supplying cooling medium to said 30 chamberQand a plug permanently sealing said passage. 3 V

9. A piston comprising head and skirt portions and a member forming a tightly closed chamber with the head and skirt portions, piston pin bosses fixed at one end to the said skirt portion and at the other end in said member, a quantity of cooling medium which is a liquid at the normal working temperature of the piston partly filling and sealed in said chamber, an oil collecting 4 groove extending annularly around the piston,

. and an oil pipe fixed at its outer end in the piston and at its inner end in said member and extending directly through said chamber to provide ,for

the removal oi oil from said groove. 1 r 5 10. A piston comprising head and skirtportions and a member forming a tightly closed chamber with the head and skirt portions, piston pin bosses. fixed at one end to the said skirt por tion and at the other end in said member, said 156 member extending up to and against the inner side of the head portion so as to brace an inner part of the head portion directly to the inner side of the piston pin bosses, a quantity of cooling medium which is a liquid at the normal working temperature of the piston partly filling and sealed in said chamber, an oil collecting groove extending annularly around the piston, and an oil pipe fixed at its outer end in the piston and at its inner end in said member and extending directly through said chamber to provide for the removal of oil from said groove.

11. A piston comprising head and skirt por- SAM D. HERON. 

